US2359478A - Controller for electric motors - Google Patents

Description

1944- R. B. HUNTER ETAL 2,359,473

CONTROLLER FOR ELECTRIC MOTORS Filed Feb. 15, 1945 L m ql L2 I r z5a" m mm W 9 Patented Oct. 3, 1944 CONTROLLER FOR ELECTRIG MOTORS Richard B. Hunter, Shorewood, and Jesse E.

Jones, Wauwatosa, Wis., assignors to Cutler- Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application February 13, 1943, Serial No. 475,7 76

12 Claims.

This invention relates to controllers for electrlc motors, and more particularly to controllers affording so-called jam protection.

In Patent No. 1,579,018, March 30, 1926, two forms of drum type motor control, one of the plain reversing type and the other of the dynamic lowering type are disclosed with jam protection which has been found very advantageous in practice. In the first mentioned form of control the protective mean is responsive, as for example when the motor stalls during operation in either direction, to re-include a predetermined amount of series resistance, whereas in the second mentioned form the protective means so functions but only when the motor is operating in hoisting direction.

In both cases when the protective means responds the same remains effective pending return of the control drum to off position.

The present invention has among its objects to improve both controllers disclosed in the afore mentioned patent, the improvements including provision for low voltage protection during running and during jamming.

Another object is to simplify the means emplayed to afford jam protection and to obtain low voltage protection through the medium of instrumentalities used for jam protection.

Another object is to provide a drum controller with jam protecting means comprising electromagnetic contactors so utilized a to take arcing to which the drum contacts otherwise would be subjected.

Another object is to enable use of a jam relay having normally open contacts, such a relay being less susceptible to shocks and vibrations, and hence more suitable for use on shipboard,

Another object is to provide jam protective mean functioning without interruption of motor torque.

Another object is to provide jam protective means applicable to different types of drum controllers, as for example a plain reversing drum or a dynamic lowering drum without change in the control circuits of said means and hence enabling for control of such circuits a standard arrangement of drum contacts.

Another object is to provide improved jam protective means applicable to controllers other than those aforementioned, whereas various other objects and advantage of the invention will hereinafter appear.

Certain embodiments of the invention are diagrammatically illustrated in the accompanying drawing which will now be described, it being understood that the embodiments illustrated are susceptible of various modifications without departing from the scope of the appended claims.

In the drawing,

Figure 1 shows the invention applied to a plain reversing controller;

Fig. 2 shows a modification of the drum portion of the jam protective means, and

Fig. 3 shows the invention applied to a dynamic lowering controller.

Referring to Fig. 1, the same shows a drum type reversing controller essentially like that shown in the aforementioned patent but with the addition of mean affording a shunt for the motor armature to be closed in the off position of the drum and in the first forward and reverse positions of the drum. More specifically Fig. 1 shows a motor M having an armature A and a series field winding F to be supplied with power from lines LI and L2. The drum comprises contact fingers l to 5 and cooperating segments la, 2a, 3a, 4a and 2b, 3b, 4b, ED for control of 'the direction of operation of the motor through reversals of the flow of current through the motor armature. Additionally the drum comprises contact fingers B and 1 and cooperating segments 6a and la, controlling an armature shunt for motor M including a resistor r. Additionally the drum includes contact finger 8, 9, H), H, I2 and I 3 and cooperatin segments 8a to I31; and 8b to I32) which afford variation and exclusion of a series resistor R for the motor when the motor is caused to operate in either direction. The aforementioned reversing contacts provid for connection of the motor to line LI, whereas the motor connections to line L2 include a drum contact finger l4 and cooperating segments Ma and Mb.

The jam protective means includes an electromagnetic contactor N, an electromagnetic contactor J and an electro-responsive jam relay JR. The contactor N has normally disengaged contacts l5 which when engaged complete circuit from line L2 to and through the windin l6 of the relay JR to drum contact finger I4. Thus line connection of the motor is dependent upon engagement of the drum finger M by one of its cooperating segments and also upon engagement of the contacts [5 of contactor N, whereas establishment of this connection subjects the winding I6 of relay JR to the motor current. The relay JR has normally disengaged contact I! which when engaged tend to complete an energizing circuit for the winding I8 of contactor J, this contactor having normally disengaged contacts I9 which when engaged establish a circuit for jam protection. This circuit extends from a tap of series resistor R, which tap for illustration is shown as drum contact I2, to and through contacts I9 of contactor J to line L2, and when contactor J responds to establish this circuit it acts through its normally engaged contacts 20 to interrupt the circuit of the winding 2! of .contactor N to cause the latter contactor through its contacts I to interrupt the first mentioned connection to line L2, As will be understood the portion of the resistor R thus reinserted for protection on jamming may be varied by adjustment of the tap of resistor R connected to the contacts of relay J.

Here it is to be noted that the jam relay JR is of the normally open type with the advantage aforementioned, and that both of the contactors J and N in respect of their main contacts I9 and I5 are of the normally open type. Moreover both contactors J and N are alike in having normally disengaged auxiliary contacts 22 and 23, respectively, and differ only in that contactor J has the aforementioned normally engaged contacts 20. Hence it will be apparent that the two contactors may be of like size.

Considering now the control means for the contactors J and N, it includes drum contact fingers 25, 2B, 2'! and 28, the contact finger 25 having a connection to line LI and having a continuously engaging segment 25a. The segments 26, 2! and 28, on the other hand, have cooperating segments 26a, 28a and 21b, 28b. Contact fingers 26 and 2! are electrically connected, and segments 28a and 26a are connected to segment 25a while segments 28!) and 21!) are also connected to segment 25a. Thus when segment 28a is engaged with finger 28 circuit is completed from line LI to segment 25a and segment 28a to contact finger 28 by conductor 29 through normally engaged contacts 20 of contactor J, to and through the winding 2| of contactor N to line L2, and the same connections are com pleted when contact finger 28 is engaged by segment 2%. One or the other of these segments engages contact finger 28 upon initial movement of the drum to start the motor in either direction, and thus provision is made for immediate energization of relay N to engage its contacts I5 whereby when the drum reaches its first operative position the motor line connections will be completed. When this occurs drum contact finger 26 will be'engaged by segment 26a or drum contact finger 2'! will be engaged by segment 21b and this establishes a connection from line LI to drum contact 25, and thence to drum contact 2! or contacts 26 by conductors 3i) and 3| to and through the now engaged contacts 23 of contactor N by conductors 32 and 29 to and through the winding 2| of contactor N as already traced. This circuit maintains the winding 2| energized when contact finger 28 is disengaged by its cooperating segment 28a or 28b. Also engagement of drum contact 26 or 2! by its respective finger provides a connection rendering closure of the contacts i! of relay JR effective to connect the winding I8 of contactor J across lines LI, L2. More particularly circuit may be traced as already described from line LI to conductor 30, thence through contacts I! to and through winding I8 to line LI.

Thus With the motor operating in either direction response of the jam relay JR to an overload current in the motor circuit energizes winding I8 to cause response of contactor J with the res lt of engaging its. contacts I9 to complete the jam protective circuit aforedescribed. At the same time contactor J through disengagement of its contacts 20 deenergizes contactor N and through engagement of its contacts 22 completes a shunt around contacts I! of relay JR. Accordingly the contactor J upon responding establishes for itself a maintaining circuit which maintains said contactor energized pending return of the drum to disengage from finger 26 or 21, as the case may be, its cooperating segment. If meanwhile the relay JR has released to disengage its contacts I! this will have no effect on contactor J, whereas when contactor J is released by the aforementioned return movement of the drum the motor is disconnected from line L2 and the starting cycle may be repeated.

Here it is to be noted that when jamming orccurs contactor N remains energized until deenergized by opening of contacts 20 of contactor J, thus providing continuous motor torque during the transfer from running connections to jam connections. Also it is tobe noted that if while contactor J or contactor N is energized there is a failure of voltage or an abnormal drop in voltage such contactors will release to entirely disconnect the motor from line L2 and to necessitate return of the drum to starting position in order to reconnect the motor to line L2. This will be apparent for the only energizing connections for the contactor N when the drum is in the running position will be interrupted by the then open contacts 23 of said contactor, whereas the connections for the winding I8 of contactor J will be opened both at the contacts I! of relay JR and at the then open contacts 22 of relay J. Further it is to be noted that with the contactor J or the contactor N closed movement of the drum to off position provides for immediate deenergization thereof, causing it to take arcing to which otherwise the drum contacts would be subjected.

Fig. 2 shows a slight modification of the drum section constituting part of the jam protective means, the modification consisting in substituting for drum segments 28a and 28b of Fig. 1 a single segment 280 to engage contact finger 28 in the off position of the drum and to disengage it when the drum is moved to either its first forward position or its first reverse position. Thus as is obvious this modification provides for energization of contactor N in off position of the drum rather than upon initial starting operation of the drum as in Fig. 1. This modified control may be desirable under certain conditions.

Fig. 3 shows a dynamic lowering drum similar to that shown in the aforementioned patent, the motor MI of Fig. 3 being shown as having an armature A, a series field F and a shunt field FI. This drum has for control of the motor circuits substantially the same contact arrangement as that of said patent, providing in off position a closed loop for the motor armature and field F, which loop includes a resistor rI, providing in its hoist positions a circuit through the motor armature and field F in series, and providing in its lowering positions a loop for the motor armature and field F with line connection of said loop such as to place the motor armature and field F in a parallel relation for reversal of the flow of current through the motor armature while maintaining the original polarity of the field F. The drum has resistance controlling contacts to afford suitable resistance control for both hoisting and lowering and like the drum of Fig. '1 it has contacts between the motor and both sides of the supply line except as regards the shunt field Fl which is permanently connected to line LI and connected to line L2 through certain of the drum contacts.

In the control of Fig. 3 the jam protective means is the same as in Fig. l, but in Fig. 3 the winding N3 of the jam relay JR is connected between the motor armature and the drum contacts which provide for connection to line Ll for hoisting. Thus this relay winding is subjected to the motor current during hoisting, whereas it is not in circuit during lowering, this providing for protection against jamming in hoisting and insuring against undesired action of the protective means in lowering. Yet as aforestated the jam protective means remains the same as in Fig. 1 even to the arrangement of the drum contacts forming part thereof.

As in Fig. 1 the contactor J of Fig. 3 controls circuit between a line L2 and a tap of the motor controlling resistor and the action of the protective means in hoisting is the same as explained in connection with Fig. 1. In lowering contactor J never responds because relay JR is not in circuit and hence is unresponsive. Thus in lowering contactor N likewise is freed from influence by relay JR through contactor J, whereas in hoisting it is subject to control by relay JR through contactor J as explained in connection with Fig. 1. Accordingly it will be obvious that the protective means while modified in action to the extent indicated otherwise functions as in Fi 1 with retention of its advantageous characteristics aforedescribed including that of affording low voltage protection.

What We claim as new and desire to secure by Letters Patent is:

1. Control means for establishing operating connections and a jam protective connection for an electric motor, comprising a normally open electroresponsive switch requiring energization for normal motor operation, a normally open electroresponsive switch to be energized to establish a jam protective motor connection and to deenergize the former electroresponsive switch, and a normally open jam relay responsive to energize the second mentioned switch.

2. The combination with an electric motor, of control means to establish selectively difierent motor connections for normal operating conditions and for protection on jam, said means comprising for selection of such connections sep-' arate electroresponsive switches each of the normally open type and further comprising a jam relay of the normally open type responsive to motor current to effect selection of the second mentioned connections.

3. In an electric motor controller, the combination with control means to establish motor connections for normal operating conditions, said means comprising a manual control device and an electroresponsive switch of the normally open type under the control of said manual device, er a normally open jam relay and a normally open electroresponsive switch responsive under the control of said relay to establish protective motor connections and to maintain such protective connections independently of said relay but subject to control by said manual device.

4. In an electric motor controller, the combination with control means to establish motor connections for normal operating conditions, said means comprising a manual control device and an electroresponsive switch of the normally open type under the control of said manual device, of a normally open jam relay and a normally open electroresponsive switch responsive under the control of said relay to establish protective motor connections and to maintain such protective connections independently of said relay, but subject to control by said manual device, the first recited electroresponsive switch being subject to deenergization by response of the last recited electroresponsive switch.

5. In an electric motor controller, the combination with control means to establish motor connections for normal operating conditions, said means comprising a manual control device and an electroresponsive switch of the normally open type under the control of said manual device, of a normally open jam relay and a normally open electroresponsive switch responsive under the control of said relay to establish protective motor connections and to maintain such protective connections independently of said relay but subject to control by said manual device, the first recited electroresponsive switch being subject to deenergization by response of the last recited electroresponsive switch, and the first recited switch when deenergized requiring for reenergization thereof manipulation of said manual device.

6. The combination with a drum controller for electric motors, of an electroresponsive switch controlled by said drum controller and coacting therewith to establish motor connections for normal motor operations, a jam relay and an electroresponsive switch under the control of said relay and said drum controller jointly to coact with said drum controller to establish protective motor connections, the last recited switch upon so functioning causing opening of the first recited switch, said drum controller having an arrangement of contact fingers and segments for control of said electroresponsive switches such that no change in drum control of said electroresponsive switches is needed whether the drum controller is of the plain reversing type with the jam relay effective for reverse motor operations or is of the dynamic lowering type with the jam relay effective only in hoist direction.

7. The combination with a drum controller for electric motors, of an electroresponsive switch controlled by said drum controller and coacting therewith to establish motor connections for normal motor operations, a jam relay and an electroresponsive switch under the control of said relay and said drum controller jointly to coact with said drum controller to establish protective motor connections, the last recited switch upon so functioning causing opening of the first recited switch, said electroresponsive switches being of the normally open type, and said drum controller having an arrangement of contact fingers and segments for control of said electroresponsive switches such that no change in drum control of said electroresponsive switches is needed whether the drum controller is of the plain reversing type with the jam relay effective for reverse motor operations or is of the dynamic lowering type with the jam relay effective only in hoist direction.

8. The combination with a drum controller for electric motors, of an electroresponsive switch of the normally open type controlled by said drum controller and coacting therewith to establish motor connections for normal motor operations, of a jam relay and an electroresponsive switch of the normally open type under the control of said relay and said drum controller jointly to coact with said drum controller to establish protective motor connections, the last recited switch upon responding causing opening of the first recited switch and establishing for itself a maintaining circuit independent of said relay but subject to control by said drum controller, said drum controller having an arrangement of contact fingers and segments for control of said electroresponsive switches such that no change in drum control of said electroresponsive switches is needed whether the drum controller is of the plain reversing type with the jam relay effective for reverse motor operations or is of the dynamic lowering type with the jam relay effective only in hoist direction.

9. The combination with a drum controller for electric motors, of an electroresponsive switch of the normally open type controlled by said drum controller and coacting therewith to establish motor connections for normal motor operations, a jam relay of the normally open type, and an electroresponsive switch of the normally open type under the control of said relay and said drum controller jointly to coact with said drum controller to establish protective motor connections, the last recited switch upon so functioning causing deenergization of the first recited switch and establishing for itself a maintaining circuit independent of said jam relay but controllable by said drum controller, and said drum controller having an arrangement of contact fingers and segments for control of said electroresponsive switches such that no change in drum control of said electroresponsive switches is needed whether the drum controller is of the plain reversing type with the jam relay effective only in the hoist direction.

10. The combination with a drum controller for electric motors, of an electroresponsive switch of the normally open type controlled by said drum controller and coacting therewith to establish motor connections for normal motor operations, a jam relay of the normally open type and an electroresponsive switch of the normally open type under the control of said relay and said drum controller jointly to coact with said drum controller to establish protective motor connections, the last recited switch upon so functioning causing deenergization of the first recited switch and establishing for itself a maintaining circuit independent of said jam relay but controllable by said drum controller, and said drum controller having an arrangement of contact fingers and segments for control of said electroresponsive switches such that no change in drum control of said electroresponsive switches is needed whether the drum controller is of the plain reversing type with the jam relay effective for reverse motor operations or is of the dynamic lowering type with the jam relay efiective only in the hoist direction, the aforementioned arrangement of contact fingers and segments being such that the first recited switch when deenergized requires for reenergization thereof positioning of said drum controller to afford motor starting protection.

11. In an electric motor controller, in combination, a normally open electroresponsive switch requiring energization for normal motor operation, a normally open electroresponsive switch to be energized to establish a jam protective connection and to deenergize the former switch, said switches under predetermined low voltage conditions insuring disconnection of the motor, and control means for said switches including a jam relay responsive to energize the second mentioned switch and requiring energization for energization of the second mentioned switch after release of the latter resulting from low voltage, and further including for control of the first mentioned switch means which may be set to prevent automatic response of the first mentioned switch upon restoration of normal voltage following release of the first mentioned switch through drop in voltage.

12. In an electric motor controller, in combination, control means to establish motor connections for normal operation, said means comprising an electroresponsive switch in the motor connections to open under predetermined low voltage conditions, and further comprising a control de-- vice for said switch having starting and running positions and requiring return to starting position for energization of said switch after its re lease as a result of low voltage, and jam protec tive means including an electroresponsive switch responsive only under jam conditions to establish an alternate motor connection and to deener ize the first mentioned switch, the second mentioned switch releasing under predetermined low voltage conditions to interrupt said alternate motor connection.

RICHARD B. HUNTER JESSE E. JONES.

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